The global positioning system (GPS), the global orbiting navigation satellite system (GLONASS), and the satellite navigation system GALILEO are examples of global navigation satellite systems (GNSS). A GNSS utilizes an earth-orbiting constellation of a plurality of satellites each broadcasting GNSS signals which indicates its precise location and ranging information. From particular locations on or near the earth, GNSS receivers may detect valid GNSS signals using a temperature compensated crystal oscillator (TCXO) and take various GNSS measurements such as pseudorange, carrier phase, and/or Doppler to calculate navigation information such as GNSS receiver positions, velocity, and time.
The GNSS receivers may be integrated within or externally coupled to mobile devices for exemplary navigation applications comprising E911, location-based 411, location-based messaging. The mobile devices may provide connections to access applications such as route tracking, multimedia communication, song downloading, instant messaging, making phone call, and/or mobile television (TV). In mobile devices there may be multiple sources of RF interference. Such interference may be present in a GNSS band and may result from unintentional sources, such as TV/FM harmonics, radar, MSS, or may result from hostile (jamming) efforts. Some interference sources are continuous, such as WCDMA transmissions or spurious emissions from other circuits, while others are pulse (burst), such as GSM or EDGE transmissions.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.